patch 8.1.0966: one terminal test is flaky

Problem:    One terminal test is flaky.
Solution:   Add to list of flaky tests.

src/testdir/runtest.vim

@@ -307,6 +307,7 @@ let s:flaky_tests = [
       \ 'Test_terminal_ansicolors_func()',
       \ 'Test_terminal_ansicolors_global()',
       \ 'Test_terminal_composing_unicode()',
+      \ 'Test_terminal_does_not_truncate_last_newlines()',
       \ 'Test_terminal_env()',
       \ 'Test_terminal_hide_buffer()',
       \ 'Test_terminal_make_change()',

src/version.c

@@ -779,6 +779,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    966,
 /**/
     965,
 /**/